Thermal module and fin unit thereof

ABSTRACT

A thermal module includes a centrifugal fan ( 20 ) and a fin unit ( 30 ). The centrifugal fan includes a casing ( 21 ) and a rotor ( 22 ) received in the casing. The casing defines an air outlet ( 24 ) through which an airflow generated by the fan flows, the air outlet having a front side outlet section ( 24   a ), a rear side outlet section ( 24   b ) and a central outlet section ( 24   c ) between the front side outlet section and the rear side outlet section. The fin unit includes a plurality of fins arranged across the air outlet of the fan. The fins arranged at the front side outlet section and the rear side outlet section of the air outlet have a longer length than the fins arranged at the central outlet section of the air outlet.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to a thermal module and a fin unit used in the thermal module, and more particularly to a thermal module for dissipating heat generated by electronic components in a portable electronic device, for example, a notebook computer.

2. Description of Related Art

Nowadays, thermal modules are provided in portable electronic devices such as portable computers in order to dissipate heat generated by heat-generating electronic components such as CPUs. Typically, a thermal module includes a fan, a fin unit arranged at an air outlet of the fan and a heat pipe with one end thereof thermally connected with the fin unit. The other end of the heat pipe thermally connects with the CPU to absorb heat therefrom. The heat absorbed by the heat pipe is transferred to the fin unit. The fan provides an airflow flowing through the fin unit to take the heat away from the CPU so as to keep the CPU at a normal working temperature.

Conventionally, the fin unit includes a plurality of fins paralleled to each other, with a channel defined between every two adjacent fins to allow the airflow flowing therethrough. Each fin has a same configuration and size. However, the speed and amount of the airflow at different segments of the air outlet of the fan is different from each other. Thus, the fins with a same size configuration cannot provide efficient heat dissipation effect.

Therefore, a thermal module with a fin unit having better heat dissipation efficiency is needed.

SUMMARY OF THE INVENTION

The present invention relates to a thermal module for dissipating heat generated by an electronic component. According to a preferred embodiment of the present invention, the thermal module includes a centrifugal fan and a fin unit. The centrifugal fan includes a casing and a rotor received in the casing. The casing defines an air outlet through which an airflow generated by the fan flows, the air outlet having a front side outlet section, a rear side outlet section and a central outlet section between the front side outlet section and the rear side outlet section. The airflow first reaches the front side outlet section, then the central outlet section and the rear side outlet section. The fin unit includes a plurality of fins arranged across the air outlet of the fan. The fins arranged at the front side outlet section and the rear side outlet section of the air outlet have a longer length than the fins arranged at the central outlet section of the air outlet. The fins of the fin unit are arranged in a manner such that a lateral side of the fin unit adjacent to the rotor of the fan forms a rectangular wave-shaped configuration and opposite lateral side of the fin unit far away from the rotor of the fan forms a linear configuration.

Other advantages and novel features of the present invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings, in which:

BRIEF DESCRIPTION OF THE DRAWINGS

Many aspects of the present apparatus can be better understood with reference to the following drawings. The components in the drawings are not necessarily drawn to scale, the emphasis instead being placed upon clearly illustrating the principles of the present apparatus. Moreover, in the drawings, like reference numerals designate corresponding parts throughout the several views.

FIG. 1 is an exploded, isometric view of a thermal module in accordance with a preferred embodiment of the present invention;

FIG. 2 is an assembled view of the thermal module of FIG. 1;

FIG. 3 is an assembled view of the thermal module of FIG. 1, with a top cover of the fan being removed; and

FIG. 4 is an assembled view of a thermal module in accordance with a second embodiment of the present invention, with a top cover of the fan being removed.

DETAILED DESCRIPTION OF THE INVENTION

Referring to FIG. 1 to FIG. 3, a thermal module in accordance with a preferred embodiment of the invention is shown. The thermal module is used for dissipating heat generated by a heat-generating electronic component (not shown) of a portable electronic device such as a notebook computer. The thermal module includes a centrifugal fan 20, a fin unit 30, a heat pipe 40 and a heat-conducting plate 50.

The fan 20 includes a casing 21 and a rotor 22 received in the casing 21. The rotor 22 includes a plurality of blades (not labeled) and rotates along an anticlockwise direction around a rotation axis thereof. The casing 21 includes a base 212 and a top cover 214 covering the base 212. The top cover 214 is a plate and defines a round inlet 23 therein for ambient air flowing therethrough into the fan 20. A rectangular air outlet 24 is defined at a side of the casing 21. The air outlet 24 includes three sections, i.e., a front side outlet section 24 a and a rear side outlet section 24 b defined at two ends of the air outlet 24, respectively, and a central outlet section 24 c defined between the front side outlet section 24 a and the rear side outlet section 24 b. During operation of the fan 20, airflow caused by the fan 20 first flows towards the front side outlet section 24 a, and then towards the central outlet section 24 c and the rear side outlet section 24 b. The airflow blows on the fin unit 30 and leaves the air outlet 24 to take the heat energy away from the fin unit 30. According to experimental analysis, the airflow adjacent to the front side outlet section 24 a and the rear side outlet section 24 b of the air outlet 24 has a larger air pressure and a higher flow rate than the airflow adjacent to the central outlet section 24 c of the air outlet 24, and the airflow adjacent to the front side outlet section 24 a of the air outlet 24 has a larger air pressure and a higher flow rate than the airflow adjacent to the rear side outlet section 24 b of the air outlet 24.

The fin unit 30 is arranged at the air outlet 24 of the fan 20. The fin unit 30 includes a plurality of first fins 31 and a plurality of second fins 32. The first and second fins 31, 32 are parallel to each other, and the first fins 31 each have a length larger than each of the second fins 32. The first fins 31 each have identical length to each other. The second fins 32 each have identical length to each other. The first fins 31 are arranged at two ends of the fin unit 30, corresponding to the front side outlet section 24 a and the rear side outlet section 24 b of the air outlet 24. The second fins 32 are arranged between the first fins 31, corresponding to the central outlet section 24 c of the air outlet 24. The second fins 32 are so arranged that each of the second fins 32 is overlapped and aligned with a rear portion of each of the first fins 31. Thus, a rectangular wave-shaped configuration is formed at one side of the fin unit 30 adjacent to the rotor 22 of the fan 20, and a linear configuration is formed at the other side of the fin unit 30 far away from the rotor 22 of the fan 20. In the present embodiment, there are more first fins 31 arranged at the front side outlet section 24 a of the air outlet 24 than arranged at the rear side outlet section 24 b of the air outlet 24. In other words, to arrange more first fins 31 at the front side outlet section 24 a of the air outlet 24 can fully exploit the larger air pressure and higher flow rate at the front side outlet section 24 a of the air outlet 24 and enhance the heat dissipation efficiency of the thermal module.

To simplify manufacturing process, each fin 31 (32) has a same structure. Each fin 31 (32) includes a rectangular-shaped main body 311 and two flanges (not labeled) horizontally extending from bottom and top ends of the main body 311, respectively. The flanges of a front fin 31 (32) abut against the main body 311 of a rear fin 31 (32) so as to form an air passage 313 between the two adjacent fins 31 (32), and the fins 31 (32) of the fin unit 30 are combined together by soldering or other means such as by engaging structures formed between adjacent fins 31 (32). For example, such engaging structures may include, without limitation, holes formed in one fin 31 (32) and engaging hooks formed on an adjacent fin 31 (32) to engage in the holes of the one fin 31 (32). A height of an outmost rear portion of the main body 311 of each fin 31, 32 far away from the air outlet 24 is larger than that of a front portion of the main body 311 of each fin 31, 32 adjacent to the air outlet 24, to thereby form a step (not labeled) on a top surface of the fin unit 30 for receiving a part of the heat pipe 40.

Since the first fins 31 each have a larger length than that of each of the second fins 32, the first fins 31 can extend more deeply into the front side outlet section 24 a and the rear side outlet section 24 b of the air outlet 24. To match the airflow distribution in the air outlet 24 and enhance the heat dissipation efficiency, the second fins 32 substantially occupy one third to a half of a total width of the air outlet 24. In the present embodiment, the second fins 32 substantially occupy a half of the total width of the air outlet 24, and the first fins 31 arranged at the front side outlet section 24 a and the rear side outlet section 24 b of the air outlet 24 substantially occupy the other half of the total width of the air outlet 24.

The heat pipe 40 is flattened and includes an evaporating portion 41 and a condensing portion 42. The evaporating portion 41 connects to the heat-conducting plate 50. The condensing portion 42 is rested on the step defined on the top surface of the fin unit 30. A height of the condensing portion 42 is substantially the same as that of the step of the fin unit 30, whereby the condensing portion 42 can be fittingly received in the step. A bottom surface of the condensing portion 42 of the heat pipe 40 thermally and physically connects to a top surface of the step of the fin unit 30, and a lateral surface of the condensing portion 42 of the heat pipe 40 also thermally and physically connects to a lateral side of the step of the fin unit 30. Thus, a contact area between the condensing portion 42 of the heat pipe 40 and the fin unit 30 is increased.

The heat-conducting plate 50 is substantially rectangular in profile, and is made of material having good thermal conductivity such as copper or aluminum. In this embodiment, the heat-conducting plate 50 is made of copper or copper alloy. The heat-conducting plate 50 defines a groove 51 along a diagonal line thereof for fittingly receiving the evaporating portion 41 of the heat pipe 40. The heat-conducting plate 50 defines a through hole 52 at a middle portion of the groove 51, so that the evaporating portion 41 of the heat pipe 40 can directly contact with the electronic component and absorb heat energy from the electronic component.

In assembly, the evaporating portion 41 of the heat pipe 40 is received in the groove 51 of the heat-conducting plate 50. The evaporating portion 41 of the heat pipe 40 and the heat-conducting plate 50 are combined together by soldering. The bottom and lateral surfaces of the condensing portion 42 are thermally and physically attached to the top and lateral surfaces of the step of the fin unit 30 by soldering. The fin unit 30 is arranged at the air outlet 24 of the fan 20.

When the thermal module is mounted to the electronic component, a bottom surface of the evaporating portion 41 of the heat pipe 40 is applied with a layer of thermal interface material so as to increase the heat conducting efficiency between the electronic component and the evaporating portion 41 of the heat pipe 40. The heat generated by the electronic component is absorbed by the heat-conducting plate 50 and the evaporation portion 41 of the heat pipe 40, and then transferred to the fin unit 30 through the heat pipe 40. The airflow generated by the fan 20 flows through the fin unit 30 and dissipates the heat to ambient air. The longer first fins 31 are arranged at the front side outlet section 24 a and the rear side outlet section 24 b of the air outlet 24, and the longer first fins 31 can extend into the air outlet 24 more deeply. Thus, a total heat dissipation area of the fin unit 30 is increased, and the airflow at the front side outlet section 24 a and the rear side outlet section 24 b of the air outlet 24 where a relatively larger air pressure and higher flow rate is present can be fully exploited. Furthermore, a distance between the blades of the fan 20 and the first fins 31 is reduced, and the airflow generated by the fan 20 can quickly reach the first fins 31; thus, the heat dissipation efficiency of the thermal module is enhanced. As the airflow adjacent to the central outlet section 24 c of the air outlet 24 has a relatively smaller air pressure and flow rate, the shorter second fins 32 being arranged at the center outer section 24 c of the air outlet 24 can effectively reduce resistance for the airflow adjacent to the central outlet section 24 c of the air outlet 24 to flow through the second fins 32.

Understandably, the fin unit 30 can have other configurations corresponding to the air outlet 24. FIG. 4 shows a second embodiment of a thermal module according to the present invention, with the top cover 214 of the fan 20 being removed. In the present embodiment, a fin unit 30 a replaces the fin unit 30 of the thermal module in the first embodiment. The fin unit 30 a includes four categories of fins with different lengths, i.e., fins 31 a, fins 31 b, fins 32 a and fins 32 b, and lengths thereof are gradually reduced in that order. The fins in each category have identical length to each other. The longest fins 31 a are arranged at the front side outlet section 24 a of the air outlet 24. The fins 31 b, which have length smaller than that of the fins 31 a, are arranged at the rear side outlet section 24 b of the air outlet 24. The fins 32 a, which have length smaller than that of the fins 31 b, are arranged at a front segment of the central outlet section 24 c adjacent to the front side outlet section 24 a of the air outlet 24. The shortest fins 32 b are arranged at a rear segment of the central outlet section 24 c adjacent to the rear side outlet section 24 b of the air outlet 24. The fins 32 a and fins 32 b substantially occupy a half of a total width of the air outlet 24, and the fins 31 a and fins 31 b substantially occupy the other half of the total width of the air outlet 24.

It is believed that the present invention and its advantages will be understood from the foregoing description, and it will be apparent that various changes may be made thereto without departing from the spirit and scope of the invention or sacrificing all of its material advantages, the examples hereinbefore described merely being preferred or exemplary embodiments of the invention. 

1. A thermal module comprising: a centrifugal fan comprising a casing and a rotor received in the casing, the casing defining an air outlet through which an airflow generated by the fan flows, the air outlet having a front side outlet section, a rear side outlet section and a central outlet section between the front side outlet section and the rear side outlet section, the airflow first reaching the front side outlet section and then the central outlet section and the rear side outlet section; and a fin unit comprising a plurality of fins arranged across the air outlet of the fan, fins arranged at the front side outlet section and the rear side outlet section of the air outlet having a length longer than that of fins arranged at the central outlet section of the air outlet, a lateral side of the fin unit adjacent to the rotor of the fan forming a rectangular wave-shaped configuration, and an opposite lateral side of the fin unit far away from the rotor of the fan forming a linear configuration.
 2. The thermal module as claimed in claim 1, wherein the fin unit comprises a plurality of first fins and a plurality of second fins, the first fins having a longer length than the second fins, the first fins arranged at the front side outlet section and the rear side outlet section of the air outlet, the second fins arranged at the central outlet section of the air outlet.
 3. The thermal module as claimed in claim 2, wherein the first fins arranged at the front side outlet section of the air outlet have more in number than the first fins arranged at the rear side outlet section of the air outlet.
 4. The thermal module as claimed in claim 1, wherein the fin unit comprises a plurality of first, second and third fins, the first fins having a longest length and arranged at the front side outlet section of the air outlet, the second fins being shorter than the first fins but longer than the third fins and arranged at the rear side outlet section of the air outlet, the third fins having a shortest length and arranged at the central outlet section of the air outlet.
 5. The thermal module as claimed in claim 4, further comprising a plurality of fourth fins arranged at the central outlet section of the air outlet, wherein the fourth fins are longer than the third fins but shorter than the second fins and arranged at a front segment of the central outlet section adjacent to the front side outlet section of the air outlet, and the third fins are arranged at a rear segment of the central outlet section adjacent to the rear side outlet section of the air outlet.
 6. The thermal module as claimed in claim 1, further comprising a heat pipe and a heat-conducting plate, the heat pipe comprising an evaporating portion connected to the heat-conducting plate and a condensing portion connected to the fin unit.
 7. The thermal module as claimed in claim 6, wherein the heat-conducting plate is substantially rectangular in profile and defines a groove along a diagonal line thereof, the evaporating portion of the heat pipe being received in the groove.
 8. The thermal module as claimed in claim 6, wherein a step is formed on a top surface of the fin unit for receiving the condensing portion of the heat pipe.
 9. A fin unit comprising a plurality of fins stacked together, wherein the fins at two ends of the fin unit have a longer length than the fins at a middle section of the fin unit, the fins at the two ends of the fin unit have identical length to each other, the fins at the middle section of the fin unit have identical length to each other, and the fins at the two ends of the fin unit and the fins at the middle section of the fin unit are arranged so as to form a rectangular wave-shaped configuration at a lateral side of the fin unit and a linear configuration at an opposite lateral side of the fin unit.
 10. The fin unit as claimed in claim 9, wherein the fin unit comprises a plurality of first fins and a plurality of second fins, the first fins being longer than the second fins, the first fins arranged at the two ends of the fin unit and the second fins arranged at the middle section of the fin unit.
 11. The fin unit as claimed in claim 10, wherein the first fins arranged at one end of the fin unit have more in number than the first fins arranged at the other end of the fin unit.
 12. The fin unit as claimed in claim 9, wherein the fin unit comprises a plurality of first, second and third fins, the first fins having a longest length and arranged at one end of the fin unit, the third fins having a shortest length and arranged at the middle section of the fin unit, the second fins being shorter than the first fins but longer than the third fins and arranged at the other end of the fin unit.
 13. The fin unit as claimed in claim 12, wherein the first fins have more number than the second fins. 